Now compiler (b138) rejects inner class as service interface if service implementation is nested static class with error:
the service definition is an inner class: Outer.Inter

Although there is no spec restriction on service interface to be inner class.

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Minimal test case:
module-info.java:
module mod {
    exports pack1;
    provides lpack1.Outer.Inter with pack1.Outer1.Implem;
}

pack1/Outer.java:
public class Outer {
    public class Inter {
    }
}

pack1/Outer1.java:
public class Outer1{
    public static class Implem extends Outer.Inter {
        public Implem () {
            new Outer().super();
        }
    }
}

This bug cause failure of tests lang/MOD/mod074